U.S. patent application number 10/285014 was filed with the patent office on 2004-05-06 for source loading apparatus for imaging systems.
Invention is credited to Hamers, Timothy F., Murray, Thomas R., Noshi, Hani Ikram.
Application Number | 20040086084 10/285014 |
Document ID | / |
Family ID | 32175063 |
Filed Date | 2004-05-06 |
United States Patent
Application |
20040086084 |
Kind Code |
A1 |
Murray, Thomas R. ; et
al. |
May 6, 2004 |
Source loading apparatus for imaging systems
Abstract
A transmission source loading apparatus for an imaging system
utilizing a transmission source is disclosed. The source loading
apparatus comprises a storage container for storing the
transmission source, and a translation device. The translation
device is adapted for advancing the transmission source from the
storage container into a holder device for use of the imaging
system. A gantry for an imaging system utilizing a transmission
source is also disclosed. The gantry includes a gantry housing, a
detector ring, a holder device for rotating the transmission source
in a rotation path associated with the detector ring, and a
transmission source loading apparatus.
Inventors: |
Murray, Thomas R.;
(Delafield, WI) ; Noshi, Hani Ikram; (Waukesha,
WI) ; Hamers, Timothy F.; (Wind Lake, WI) |
Correspondence
Address: |
HUNTON & WILLIAMS
Intellectual Property Department
1900 K Street, N.W.
Washington
DC
20006-1109
US
|
Family ID: |
32175063 |
Appl. No.: |
10/285014 |
Filed: |
October 31, 2002 |
Current U.S.
Class: |
378/196 |
Current CPC
Class: |
A61B 6/107 20130101 |
Class at
Publication: |
378/196 |
International
Class: |
H05G 001/02 |
Claims
1. A transmission source loading apparatus for an imaging system
utilizing a transmission source, comprising: a storage container
for storing the transmission source; and a translation device, the
translation device being adapted for advancing the transmission
source from the storage container into a holder device for use of
the imaging system.
2. The apparatus of claim 1, wherein an access door is located
proximate to the storage container, the translation device being
adapted for advancing at least a first portion of the transmission
source into the holder device through an access port exposed by
displacing the access door.
3. The apparatus of claim 2, wherein the translation device further
includes: a drive assembly; and a source gripping device for
retaining at least a second portion of the transmission source, the
drive assembly being adapted for advancing the source gripping
device to a loading point proximate to the access port.
4. The apparatus of claim 3, wherein the source gripping device
includes: a housing; a first magnet portion fixed to the housing,
the first magnet portion having a first magnetic holding force; and
an electromagnet portion fixed to the housing, the electromagnet
portion producing a second magnetic holding force when
activated.
5. The apparatus of claim 4, wherein the holder device includes: a
housing; a source receiving portion disposed in the housing; and a
third magnet portion fixed to the housing, the third magnetic
portion having a third magnetic holding force.
6. The apparatus of claim 5, wherein the third magnetic holding
force is greater than the first magnetic holding force.
7. The apparatus of claim 6, wherein the holder device and source
gripping device are adapted for alignment at the loading point such
that when the at least first portion of the transmission source is
advanced into the source receiving portion of the holder device,
the third magnetic holding force being greater than the first
magnetic holding force, the transmission source is retained by the
source receiving portion of the holder device.
8. The apparatus of claim 5, wherein the first magnetic holding
force and the second magnetic holding force combined are greater
than the third magnetic holding force.
9. The apparatus of claim 8, wherein the holder device and source
gripping device are adapted for alignment at the loading point such
that when the transmission source is advanced into the source
receiving portion of the holder device, the first magnetic holding
force and the second magnetic holding force combined being greater
than the third magnetic holding force, the transmission source is
retained by the source gripping device.
10. The apparatus of claim 3, wherein the drive assembly includes:
a carriage mounted on a lead screw, the carriage controllably
translated along the lead screw by a control portion.
11. The apparatus of claim 10, wherein the control portion includes
a servo motor.
12. The apparatus of claim 10, wherein the source gripping device
is mounted on the carriage.
13. The apparatus of claim 2, wherein the access door is coupled to
a door drive assembly, the door drive assembly being adapted for
displacing the access door to expose the access port.
14. The apparatus of claim 13, wherein the door drive assembly
includes: a door mount fixed to the access door; a track assembly;
and a control device being adapted for controllably displacing the
door mounted along the track assembly.
15. The apparatus of claim 14, wherein the control device includes
a pulley timing belt system coupled to the door mount for
controllably displacing the access door.
16. The apparatus of claim 1, wherein the translation device is
adapted for advancing the transmission source from the storage
container into the holder device along a single axis of motion.
17. A gantry for an imaging system utilizing a transmission source
comprising: a gantry housing; a detector ring fixed to the gantry
housing; a holder device, the holder device being adapted for
rotating the transmission source in a transmission path associated
with the detector ring; and a transmission source loading apparatus
including, a storage container for storing the transmission source,
and a translation device, the translation device being adapted for
advancing the transmission source from the storage container into a
holder device for use of the imaging system.
18. The gantry of claim 17, the storage container having an access
door located at a first end of the storage container, the
translation device being adapted for advancing at least the first
portion of the transmission source into the holder device through
an access port created by displacing the access door.
19. The gantry of claim 17, wherein the translation device is
adapted for advancing the transmission source from the storage
container into the holder device along a single axis of motion.
20. A transmission source loading apparatus for an imaging system
utilizing a transmission source, comprising: means for storing the
transmission source; and means for advancing the transmission
source from the storage means into a means for rotating the
transmission source for use of the imaging system.
21. The apparatus of claim 20, wherein an access door is located
proximate to the storage means, the means for advancing the
transmission source being adapted for advancing at least a first
portion of the transmission source into the means for rotating
through an access port exposed by displacing the access door.
22. The apparatus of claim 20, wherein the means for advancing the
transmission source is adapted for advancing the transmission
source from the storage means into the holder means along a single
axis of motion.
23. A gantry for an imaging system utilizing a transmission source
comprising: a gantry housing; a detector ring fixed to the gantry
housing; means for rotating the transmission source in a
transmission path associated with the detector ring; and a
transmission source loading apparatus including, means for storing
the transmission source; and means for advancing the transmission
source from the storage means into the means for rotating the
transmission source for use of the imaging system.
24. The gantry of claim 23, wherein the means for advancing the
transmission source is adapted for advancing the transmission
source from the storage means into the holder means along a single
axis of motion.
25. A storage container for a source loading apparatus, comprising:
a first shield portion hingedly attached to a bottom portion; and a
second shield portion hingedly attached to the bottom portion,
wherein the first shield portion and the second shield portion are
engageable for securing the storage container in a closed
position.
26. The storage container of claim 25, further including: an access
port member, wherein the first shield portion and the second shield
portion engage at least a portion of the access port member when
the storage container is in the closed position.
27. The storage container of claim 25, further including an access
port member having an access port formed therein.
28. The storage container of claim 25, further including a handle
attached to the first shield portion or the second shield
portion.
29. The storage container of claim 25, further including a pin
attached to the first shield portion, wherein the first shield
portion and the second shield portion are engageable when the pin
engages a pin slot attached to the second shield portion.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates generally to systems and methods for
loading transmission sources used in imaging systems.
[0002] Imaging systems play an important role in the practice of
medicine and the administration of health care to patients. Imaging
systems allow physicians to diagnose otherwise undetectable
problems throughout the body. For example, Positron Emission
Tomography ("PET") imaging systems allow a physician to examine the
heart, brain, and other organs, by producing images that show the
chemical functioning of an organ or tissue. Most PET imagers
operate by placing a patient on a cradle and moving the cradle into
the gantry's patient bore, where the scanning takes place. The
patient bore is lined by a series of detector rings that gather
imaging data when the imager is scanning. The detector rings
utilize crystals to measure coincidence events when radiation is
released into the scanning area. The necessary radiation is
released when a transmission source, or radioactive source, is
rotated by a transmission ring around the inside perimeter of the
detector rings. The data gathered by the crystals is used to
produce the medical image of the patient's body.
[0003] The transmission source is often constructed of radioactive
material, which can be harmful to humans after prolonged exposure.
Accordingly, the transmission source for an imaging system must be
kept within a shielded container until the imaging system is ready
for use. Transferring the transmission source from the shielded
container to a location where it can be rotated around the detector
rings has presented several problems.
[0004] For example, some conventional PET imaging systems utilize a
robotic arm to transfer the transmission source from the shielded
storage container to the transmission ring. One disadvantage of the
robotic arm is that it requires several mechanical movements
including both rotation and translation. More specifically, the
robotic arm must extend into the storage container to take hold of
the transmission source, and pull out of the storage container
without dropping the transmission source or letting it come into
contact with any other structures. Outside the storage container,
the robotic arm must once again move into position with the
transmission ring. Each of these difficult movements is controlled
by complex logic sequences governing the movements of the armature
and transmission source. In addition, the reliability of this
robotic armature is highly dependant on several geometric and
dimensional tolerances based on the length of the robotic armature,
and the cantilevered mount attached to the translation gearbox. The
accuracy and reliability of the robotic armature is extremely
important given that the transmission source must be precisely
positioned within the transmission ring while in use, and in the
storage container when not in use.
[0005] An additional disadvantage is that these robotic arms
utilize a mechanical claw-like means, which must hold and at
appropriate times release the transmission source. This design
occasionally results in the transmission source being dropped
during transfer.
[0006] For at least these reasons, there is a need for the
continuous support of transmission sources at all times during
loading and unloading. There is also the need for simplifying the
rotational and translational paths the transmission source must
take when moving from storage to loading positions. There is also a
need for simplifying and improving the mechanical means used to
grip and hold the transmission source during loading and unloading.
Overcoming these disadvantages will lower the risk of the
transmission source being dropped, which in turn will reduce
imaging system downtime.
[0007] The invention provides apparatuses, systems and methods for
source loading in imaging systems, that overcome the disadvantages
of known systems and methods while offering features not present in
known systems and methods.
BRIEF SUMMARY OF THE INVENTION
[0008] In accordance with one embodiment of the invention, a
transmission source loading apparatus for an imaging system
utilizing a transmission source is disclosed. The source loading
apparatus comprises a storage container for storing the
transmission source, and a translation device. The translation
device is adapted for advancing the transmission source from the
storage container into a holder device for use of the imaging
system.
[0009] In another embodiment of the invention, a gantry for an
imaging system utilizing a transmission source is disclosed. The
gantry includes a gantry housing, a detector ring, a transmission
ring and holder device for rotating the transmission source in a
rotation path associated with the detector ring, and a transmission
source loading apparatus. The source loading apparatus includes a
storage container for storing the transmission source, and a
translation device. The translation device is adapted for advancing
the transmission source from the storage container into a holder
device for use of the imaging system.
[0010] In yet another embodiment of the invention, a transmission
source loading apparatus for an imaging system utilizing a
transmission source is disclosed. The apparatus is comprised of a
means for storing the transmission source and a means for advancing
the transmission source from the storage means into a means for
rotating the transmission source for use of the imaging system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention can be more fully understood by
reading the following detailed description of the presently
preferred embodiments together with the accompanying drawings, in
which like reference indicators are used to designate like
elements, and in which:
[0012] FIG. 1 is a perspective view of an illustrative imaging
system in accordance with one embodiment of the invention;
[0013] FIG. 2 is a side view of an imaging system in accordance
with one embodiment of the invention;
[0014] FIG. 3 is a perspective view of a source loading apparatus
in accordance with one embodiment of the invention;
[0015] FIG. 4 is a perspective view of a source loading apparatus
in accordance with one embodiment of the invention;
[0016] FIG. 5a is a perspective view of a source gripping device in
accordance with one embodiment of the invention;
[0017] FIG. 5b is an exploded view of the source gripping device of
FIG. 5a in accordance with one embodiment of the invention;
[0018] FIG. 6 is a planar sectional view of a source gripping
device with transmission source in accordance with one embodiment
of the invention;
[0019] FIG. 7 is an exploded perspective view of translation device
in accordance with one embodiment of the invention;
[0020] FIG. 8 is a planar view of a source loading apparatus in
accordance with one embodiment of the invention;
[0021] FIG. 9a is a perspective view of a source holder device in
accordance with one embodiment of the invention;
[0022] FIG. 9b is an exploded view of the source holder device of
FIG. 9a in accordance with one embodiment of the invention;
[0023] FIG. 10 is a planar view of a source loading apparatus in
accordance with one embodiment of the invention; and
[0024] FIG. 11 is a planar view of a source loading apparatus in
accordance with one embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0025] A source loading apparatus for an imaging system is
disclosed in which a transmission source is advanced from a storage
container, through the use of a translation device, into a holder
device so that the transmission source can be rotated around the
inside perimeter of the detector rings. The source loading
apparatus provides a mechanism whereby the transmission source
travels back and forth along one axis of motion, from a storage
position to a loading position (i.e., from the storage position,
rotation or adjustment vertically or side to side is not needed to
advance transmission source into holder device). In the storage
position, the transmission source, which is comprised of
radioactive material, is safely shielded within the storage
container. When needed for scanning, the transmission source is
advanced from within the storage container into a holder device
attached to the transmission ring. Once scanning is complete, the
transmission source is removed from the holder device and returned
to its storage position inside the storage container.
[0026] FIG. 1 is a perspective view of an illustrative imaging
system in accordance with one embodiment of the invention. Imaging
system 10 is shown with gantry 12 and patient table 18. As shown in
FIG. 1, gantry 12 includes patent bore 14, which is partially
defined by detector ring 16. Table 18 is shown with patent 22
resting in the patient cradle 20. Patient cradle 20 is adapted to
move into patient bore 14 such that the patient 22 can be scanned
by the detector ring 16.
[0027] In this embodiment of the invention, imaging system 10 is a
combined PET and Computed Tomography (CT) scanner. It should be
appreciated that further embodiments of the imaging system may be
PET or CT alone.
[0028] FIG. 2 is a side view of the imaging system of FIG. 1.
Within gantry 12, transmission ring 17 is adapted to rotate a
transmission source around the detector ring 16 so that a series of
detectors in detector ring 16 may be used to obtain an image of
patient 22 being scanned. A source loading apparatus 50 is used to
store the transmission source when not in use, and positioned
adjacent to transmission ring 17. Source loading apparatus 50 is
adapted for advancing the transmission source into a Source holder
device attached to transmission ring 17 for use in scanning. The
holder device is attached to transmission ring 17 such that when
the transmission source is rotated around the patient bore 14,
detector ring 16 gathers data on the coincidence events observed
and transmits the data to a processing machine for producing the
desired imaging.
[0029] FIGS. 3 and 4 are perspective views of a source loading
apparatus in accordance with one embodiment of the invention. As
shown in FIG. 3, source loading apparatus 50 includes storage
container 100, translation device 200, and door assembly 300.
Storage container 100 provides the housing in which the
transmission source 55 is kept when not being used.
[0030] In this embodiment, transmission source 55 is a source pin
including a radioactive material, such as positron emitter
Germanium 68. Transmission source 55 is cylindrically shaped and,
configured for insertion into a holder device so that transmission
source 55 can be rotated around the detector ring of the imaging
system. Transmission source 55 may also include a radioactive
portion and a non-radioactive portion, for insertion into a source
gripping device. Storage container 100 is constructed of a
radioactive shielding material, such as lead or tungsten, to
prevent the penetration of radiation from storage container 100
when transmission source 55 is not in use.
[0031] Storage container 100 is comprised of right shield portion
102, left shield portion 104, bottom shield portion 103, and access
port member 114. As shown in FIG. 3, storage container 100 is in
the open position, i.e., the right shield 102 and left shield 104
are not engaged. Right shield 102 and left shield 104 are both
hingedly attached to bottom portion 103 by pivot rod hinges 112,
such that right shield 102 and left shield 104 are adapted to
engage each other to form an elongate channel in which the
translation device 200 is provided. As shown in FIG. 3, in this
embodiment, right shield 102 and left shield are l-shaped members,
rotatable around the pivot point of pivot rod hinge 112.
[0032] Right shield 102 and left shield 104 are secured together
when pin 106, attached to the left shield 104 on the outside of
storage container 100, engages pin slot 108, attached to the right
shield 102. In this embodiment, a sheet metal piece is attached to
the upper portion of both right shield 102 and left shield 104,
each sheet metal piece including pin slots for receiving pin 106.
To engage the right shield 102 and left shield 104, pin 106 is
inserted through a pin slot in the metal piece attached to left
shield 104, and further through a pin slot 108 on the metal piece
attached to right shield 102, before it releasably secures both
shield portion together. It should be appreciated that additional
pin and pin slot arrangements may be utilized on the shield
portions to provide for additional securing force between the two
portions.
[0033] Pivot rod hinges 112 are attached to right shield 102 and
left shield 104 to facilitate the opening of storage container 100
when pin 106 is disengaged from pin slot 108. Right shield 102 and
left shield 104 also have shoulders, or recesses, formed within the
front edge of each, such that when storage container 100 is closed,
the shoulders of right shield 102 and left shield 104 engage, or
enclose a portion of, access port member 120. Access port member
120 is a channel-type member, through which an access port 115 is
formed such that transmission source 55 is advanced into the holder
device of the transmission ring.
[0034] It should be appreciated that the mechanical parts that
attach right shield 102, bottom 103, and left shield 104 to the
pivot rod hinges 112, are used in a manner that does not affect the
shielding properties of storage container 100. When right shield
102 and left shield 104 are engaged, the interior of storage
container 100 is enclosed with the exception of access port 115
within access port member 120. However, as shown in FIG. 3, access
door 301, of door assembly 300 covers access port 115 when
transmission source 55 is in the storage position inside storage
container 100.
[0035] Although not illustrated, it should be appreciated that
further embodiment for the storage container may be utilized that
allow for the storage of the transmission source when not is use.
In one such embodiment, the storage container may comprise a
container housing and a lid. The container housing may include a
rear wall, side walls, and a front wall, which forms the base of a
lid seat. The lid would be configured to fit within the lid seat,
such that the lid provides the top of the storage container. The
container housing would further include a bottom, from which each
wall extends upwardly. The front wall would have an opening formed
within it, i.e., an access port, through which the transmission
source would be advanced into the holder device of the transmission
ring. When the lid is placed on the lid seat, the interior of the
storage container would be enclosed with the exception of the
access port. An access door, of the door assembly would cover the
access port when the transmission source is in storage position
inside storage container.
[0036] Translation device 200 also includes source gripping device
230, which is responsible for securing transmission source 55 by
retaining a portion of transmission source 55 using magnetic
forces. When enclosed and shielded by storage container 100 and
access door 301, transmission source 55 is considered to be in a
storage position. Illustratively, FIG. 3 depicts source loading
apparatus 50 and transmission source 55 in a storage position, with
the exception that right shield 102 and left shield 104 are not
engaged.
[0037] To allow the transmission source to be stored within and
advanced out from within storage container 100, portions of
translation device 200 are located within storage container 100.
Translation device 200 includes drive assembly 210 and source
gripping device 230. Drive assembly 210 advances source gripping
device 230 back and forth between the storage position and loading
position. Source gripping device 230 holds transmission source 55
in the storage position and transfers transmission source 55 to the
holder device for scanning.
[0038] As described above, FIG. 3 depicts a storage position of
transmission source 55. In this position, access door 301 covers
access port 115 to enclose the interior of storage container 100.
Similar to storage container 100, access door 301 is also
constructed of a radioactive shielding material, such as lead or
tungsten. When signaled, door drive assembly 310 moves access door
301 from its storage position covering access port 115 to its
loading position wherein access port 115 is exposed such that
transmission source 55 can be advanced through access port 115, as
shown in FIG. 4.
[0039] In this embodiment, door assembly 300 is comprised of access
door 301 and door drive assembly 310. As shown in FIG. 3, door
drive assembly 310 utilizes a pulley/timing belt system to move
access door 301 and expose access port 115. The pulley/timing belt
system includes control device 320, connectors 321, groove pulleys
322, timing belt 324, belt fastener 326 and motor 328. Timing belt
324 is driven by groove pulleys 322, which are powered by motor 328
under the command of control device 320. Belt fastener 326, or belt
crimp, attaches to timing belt 324, and is also affixed to door
mount 312. A portion of the lower half of access door 301 is
secured to door mount 312. Accordingly, when timing belt 324 is
driven by motor 328 using groove pulleys 322, belt fastener 326
pulls door mount 312 along, which in turn moves access door 301
aside, exposing access port 115.
[0040] Control device 320 is in communication with control portion
216, such that when source gripping device 230 is advanced forward,
control device 320 receives a signal to move access door 301. In
this embodiment of the invention, control device 320 is a Printed
Circuit Board ("PCB"). It should be appreciated that control
portion 216 may send a signal indicating movement of the
transmission source to a processing machine, which in turn will
send a command to control device 320 through connectors 321 to move
access door 301.
[0041] As shown in FIG. 4, transmission source 55 and source
gripping device 230 are no longer in the storage position depicted
in FIG. 3. Right shield 102 and left shield 104 are engaged,
enclosing the interior of storage container 100. Transmission
source 55 and source gripping device 230 are in a loading position,
wherein source gripping device 230 is at a loading point and
adapted for alignment with the holder device of the transmission
ring. In the loading position, both source gripping device 230 and
the holder device would each retain a portion of the transmission
source 55, which would have been inserted into the holder device by
the forward advancement of source gripping device 230. As shown in
FIG. 4, access door 300 has been moved aside exposing access port
115 and allowing source gripping device 230 to advance through the
opening. It should be appreciated that the loading position
depicted in FIG. 4 may also represent the positioning of source
gripping device 230 at the unloading position, in which source
gripping device 230 grabs transmission source 55 from the holder
device and retracts inside storage container 100.
[0042] As shown in FIG. 4, right shield 102 and left shield 104
have handles 110 attached to their side portions. Handles 110
facilitate the opening of storage container 100 when right shield
102 and left shield 104 are separated. Handles 110 may also be
utilized as stands when right shield 102 and left shield 104
separate and rotate away from the other using pivot rod hinges 112.
With pivot rod hinges 112, right shield 102 and left shield 104 are
attached to the bottom portion (not illustrated) of storage
container 100.
[0043] FIG. 5a is a perspective view of a source gripping device in
accordance with one embodiment of the invention. FIG. 5b
illustrates an exploded view of the source gripping device of FIG.
5a. In this embodiment, source gripping device 230 is comprised of
housing 232, electromagnet portion 234, magnet ring 240 and magnet
cover 242. Electromagnet portion 234 and magnet ring 240 provide
the magnetic holding forces utilized by the source gripping device
230 in the storage, loading and unloading of transmission
sources.
[0044] As shown in FIG. 5b, electromagnet portion 234 is comprised
of electromagnet housing 236 and electromagnet core 238. When
assembled, electromagnet housing 236 substantially encloses
electromagnet core 238, and is secured within cavity 233 of housing
232. In this embodiment, electromagnet core 238 is a tubular member
with a disc-shaped head and an inner diameter configured for
receiving at least a portion of the transmission source. The
tubular member of electromagnet core 238 is constructed of a series
of copper windings forming a coil around a steel sleeve.
Electromagnet core 238 is designed to slide within cavity 237 of
electromagnet housing 236. Connector 235 is attached to
electromagnet housing 236 and provides the electricity to the
electromagnet 234 so that it can be energized.
[0045] Magnet ring 240 is aligned adjacent to the disc-shaped head
of electromagnet core 238, and magnet cover 242 is affixed to
housing 232, enclosing the electromagnetic portion 234 and magnet
ring 240. In this embodiment, magnet cover 242 is constructed of
stainless steel sheet metal, and suitable fasteners, such as screws
or bolts, may be inserted into holes 244 to affix magnet cover 242
to housing 232.
[0046] Source gripping device 230, utilizes inner cavity 231 for
receiving at least a portion of the transmission source. Inner
cavity 231 of source gripping device 230 is defined by bore sleeve
239 of electromagnet core 238, and openings 241 and 243, extending
through magnet ring 240 and magnet cover 242, respectively. In this
embodiment, source gripping device 230 is formed such that a
transmission source can be inserted into cavity 231, which
comprises the retaining portion of source gripping device 230.
Sensor 246 is affixed to the rear of housing 232 and is adapted for
detecting the presence of the transmission source within inner
cavity 231. Sensor 246 may be axially aligned on the rear of
housing 232 and may comprise a normally
open--Positive-Negative-Positive (PNP) inductive sensor.
[0047] As described above, magnet ring 240 and electromagnet
portion 234 provide the magnetic holding forces used in the
securing, loading and unloading of transmission sources in
accordance with an exemplary embodiment of the invention. FIG. 6 is
a planar sectional view of source gripping device of holding a
transmission source in accordance with one embodiment of the
invention. As shown in FIG. 6, transmission source 55 includes a
non-radioactive portion 56, which source gripping device 230 is
retaining at least a part of, and a radioactive portion 57, which
is designed to release the radiation used in the imaging system.
Magnet ring 240 is a permanent magnet and provides a first magnetic
holding force for securing the transmission source 55. In this
embodiment, magnet ring 240 is constructed of Neodymium 37, and
possesses a magnetic holding force equal to 1.2 Ibf. However, it
should be appreciated that magnet ring 240 may be constructed of
any suitable magnetized material having an associated holding
force.
[0048] Electromagnet portion 234 is designed to produce a magnetic
holding force upon activation, i.e., when an electric current is
passed through the windings of electromagnet core 238. Together,
the magnetic holding forces of magnet ring 240 and electromagnet
portion 234 produce a combined magnetic holding force greater than
the magnetic holding force of the transmission ring's holder
device, described in further detail below.
[0049] It should be appreciated that source gripping device 230 is
designed such that when transmission source 55 is in its storage
position (as depicted in FIG. 3), the only magnetic holding force
needed to secure transmission source 55 in the inner cavity 231 of
source gripping device 230 is that produced by magnet ring 240.
[0050] To load the transmission source, source gripping device 230
is advanced to a loading position where it is aligned with the
holder device. During this alignment, the radioactive portion 57 of
transmission source 55 is inserted into the holder device. The
holder device utilizes a permanent magnet ring, or a series of
magnet rings, to produce a magnetic holding force greater than the
holding force of magnet ring 240 alone. Consequently, during the
loading process, when both source gripping device 230 and the
holder device are holding a portion of the transmission source, the
stronger magnetic holding force of the holder device retains
transmission source 55 when source gripping device 230 is retracted
into storage container 100. It should be appreciated that the
holder device may utilize any combination of magnets to retain the
transmission source from source gripping device 230, as long as the
combination produces a holding force greater than that of magnet
ring 240, but less than the combined holding force of magnet ring
240 and electromagnet portion 234.
[0051] After loading of the transmission source into the holder
device, source gripping device 230 is driven back away from the
holder device, leaving the transmission source in the holder device
so that it may be utilized in the imaging system. Once the scanning
is complete and transmission source 55 is no longer needed, source
gripping device 230 is once again aligned with the holder device so
that each is holding a portion of transmission source 55.
Electromagnet portion 234 is then energized producing a magnetic
holding force that either alone, or in combination with the holding
force of magnet ring 240, overpowers the Source holder device's
magnetic holding force. Thus, electromagnet portion 234 allows
source gripping device 230 to pull transmission source 55 from the
holder device and return the transmission source 55 to its storage
position within the storage container. Therefore, source gripping
device 230 is adapted for utilizing at least two different magnetic
holding forces, including: (1) produced by magnet ring 240, such
that it is overpowered by the holder device upon source loading,
and (2) the combined force produced upon energizing of
electromagnet portion 234, which is stronger than the holder device
holding force for unloading.
[0052] FIG. 7 is a perspective view of the translation device of
FIGS. 3 and 4 in accordance with one embodiment of the invention.
As shown in FIG. 7, translation device 200 is illustrated in an
exploded view. Translation device 200 comprises drive assembly 210
and source gripping device 230. In this embodiment of the
invention, drive assembly 210 includes lead screw 212, bearing
blocks 213, carriage 214, adapter plate 215 and control portion
216. Source gripping device 230 is mounted on adapter plate 215,
which is designed for attachment to carriage 214. Carriage 214 is
slidably attached to lead screw 212. Lead screw 212 extends between
bearing blocks 213, which are adapted for positioning inside the
storage container at the base of the rear and front walls. Control
portion 216 controls the movement of carriage 214 along the lead
screw 212, such that when the transmission source is needed for
scanning, control portion 216 drives carriage 214 forward to a
loading point where the source gripping device loads the
transmission source into the holder device.
[0053] Control portion 216 utilizes motor 218 to drive carriage 214
along the lead screw 212. Motor 218 is electronically coupled to
and powers carriage 214 along lead screw 212. Motor 218 is attached
to motor mount 220. In this embodiment, motor 218 is a brushless DC
servo motor adapted for electronic coupling to and communication
with a processing machine controlling the operation of an imaging
system. Accordingly, motor 218 may receive input from and generate
output to a processing machine through connectors 219, or ribbon
cable 223, which is in communication with circuit board 222.
[0054] In the storage position, the access door covers the access
port. When the transmission source must be loaded, the access door
is moved aside by the door drive assembly. Accordingly, control
portion 216 utilizes sensor 224 to alert the door drive assembly
when carriage 214 and source gripping device 230 begin advancing
towards the access port. Sensor 224 signals the door drive assembly
to move the access door aside to expose the access port through
which the transmission source will travel. In this embodiment,
sensor 224 may comprise an optical sensor, or switch, that detects
when carriage 214 or source gripping device 230 are moved from the
storage position towards the loading position through coordination
with actuator 225. It should be appreciated that sensor 224 may
signal the movement of carriage 214 or source gripping device 230
by sending an electronic signal to a processing machine, which in
turn will command the door drive assembly to move access door.
[0055] FIG. 8 is a planar sectional view of a source loading
apparatus with transmission source and transmission ring in
accordance with one embodiment of the invention. As shown in FIG.
8, source loading apparatus 50 is in the storage position, i.e.,
transmission source 55 is held by source gripping device 230 and
both are enclosed within storage container 100. Source loading
apparatus 50 is also aligned with holder device 400, which is
attached to transmission ring 17, and positioned to deliver
transmission source 55 into holder device 400 attached to
transmission ring 17. Holder device 400 is attached to transmission
ring 17 such that when transmission source 55 is delivered into
holder device 400, transmission ring 17 rotates the holder device
400 around the patient bore, and the detector ring gathers the
imaging data.
[0056] FIG. 9a is a perspective view of the source holder device of
FIG. 8 in further detail in accordance with one embodiment of the
invention, as shown in an exploded view in FIG. 9b. Holder device
400 includes housing 402, magnet rings 410 and 412, and cover 414.
Housing 402 includes a recess 404 from which cylinder member 406
extends. Cylinder member 406 has bore 407 that extends axially
through housing 402. Recess 404 and cylinder member 406 are
configured such that magnet rings 410 and 412 can be fitted over
the outer perimeter of cylinder member 406 within recess 404. Once
the magnet rings 410 and 412 are secured on cylinder member 406,
cover 414 is affixed to housing 402, enclosing the magnet rings and
providing an axial bore through holder device 400 for receiving the
transmission source from the source gripping device.
[0057] As described above, magnet rings 410 and 412 each possess a
magnetic holding force. The combined magnetic holding force of
magnet rings 410 and 412 is greater that that possessed by the
magnet ring located within source gripping device 230, thus
facilitating loading of the transmission source in the holder
device 400. However, the combined magnetic holding force of magnet
rings 410 and 412 is not greater than that of the magnet ring
located within source gripping device 230 combined with the
electromagnet holding force produced when the electromagnet portion
234 within source gripping device 230 is energized. It should be
appreciated that although holder device 400 has been shown with two
magnet rings, any suitable number of magnet rings or strength of
magnet(s) may be utilized so that the magnetic holding force of the
holder device 400 is greater than the magnetic holding force
produced by the magnet ring 240 in the source gripping device 230,
but less than the combined magnetic holding force of the magnet
ring 240 and electromagnet portion 234 in the source gripping
device 230.
[0058] FIGS. 10 and 11 are planar sectional views of source loading
apparatuses in accordance with one embodiment of the invention. In
FIG. 10, source gripping device 230 has been advanced forward to
align with holder device 400, such that both source gripping device
230 and holder device 400 are each retaining a portion of
transmission source 55. Once loading is complete, source gripping
device 230 retracts into storage container 100, as shown in FIG.
11. However, as described above, transmission source 55 remains
held in holder device 400 because of the greater combined magnetic
holding force of the magnet rings 410 and 412.
[0059] When transmission source 55 is to be returned to the storage
position, as source gripping device 230 and holder device 400
realign in the loading position shown in FIG. 10. The electromagnet
portion 234 of source gripping device 230 is energized, which
produces a combined magnetic holding greater than that of magnet
rings 410 and 412. Thus, source gripping device 230 removes
transmission source 55 from holder device 400 and retracts into
storage container 100, as shown in FIG. 8.
[0060] FIGS. 1-11 illustrate an embodiment of the invention in
which a source loading apparatus utilizes a translation device to
advance a transmission source from a storage position inside a
shielded storage container to a loading position aligned with the
holder device of a transmission ring. In further embodiments of the
invention, the translation device may employ a different drive
assembly to advance the source gripping device carrying the
transmission source. For example, the source gripping device may be
mounted on a rack and pinion assembly, which would move the source
gripping device back and forth from the storage and loading
positions. Likewise, in other embodiments, the door assembly may
utilize mechanisms other than the pulley timing belt system to move
the access door to expose the access port. For example, the door
drive assembly may include a rack and pinion gear assembly that
moves the access door when the source gripping device is advanced
forward. Additionally, a worm/worm gear assembly can be utilized
with a lead screw that advances a carriage forward with the source
gripping device and drives the access door aside.
[0061] As described above with reference to various embodiments of
the invention, the source loading apparatus, or various components
thereof, may receive input from or send output to a processing
machine to accomplish the desired function of the invention. It
should be appreciated that an imaging system, gantry, source
loading apparatus, or components thereof, may receive commands from
a controller workstation through the processing machine, or other
mechanical components electronically coupled to or in communication
with a processing machine. As used herein, the term "processing
machine" is to be understood to include at least one processor that
uses at least one memory. The memory stores a set of instructions.
The instructions may be either permanently or temporarily stored in
the memory or memories of the processing machine. The processor
executes the instructions that are stored in the memory or memories
in order to process data. The set of instructions may include
various instructions that perform a particular task or tasks, such
as those tasks described. Such a set of instructions for performing
a particular task may be characterized as a program, software
program, or simply software. As noted above, the processing machine
executes the instructions that are stored in the memory or memories
to process data. This processing of data may be in response to
commands by a user or users of the processing machine, in response
to previous processing, in response to a request by another
processing machine and/or any other input, for example.
[0062] The processing machine used to implement the invention may
be a general purpose computer. However, the processing machine
described above may also utilize any of a wide variety of other
technologies including a special purpose computer, a computer
system including a microcomputer, mini-computer or mainframe, a
programmed microprocessor, a micro-controller, an integrated
circuit, a logic circuit, a digital signal processor, a
programmable logic device, or any other device or arrangement of
devices that is capable of implementing the invention.
[0063] Many embodiments and adaptations of the present invention
other than those herein described, as well as many variations,
modifications and equivalent arrangements, will be apparent from or
reasonably suggested to those skilled in the art by the present
invention and foregoing description thereof, without departing from
the substance or scope of the invention.
[0064] While the present invention has been described here in
detail in relation to its exemplary embodiments, it is to be
understood that this disclosure is only illustrative and exemplary
of the present invention and is made to provide an enabling
disclosure of the invention. Accordingly, the foregoing disclosure
is not intended to be construed or to limit the present invention
or otherwise to exclude any other such embodiments, adaptations,
variations, modifications or equivalent arrangements.
* * * * *